Predicting the value of \(M_W\)  is based on matching the 4-Fermi theory muon lifetime with the 1-loop calculation using the full Lagrangian of the theory (see [1]}, [2]}, [3]}, [4]} for more detailed accounts). The matching yields an expression connecting the experimentally measured Fermi coupling constant \(G_F\)  to the parameters of the \(B_3-L_2\)  model:
\(\frac{G_F}{\sqrt{2}} = \frac{e^2}{8 M_W^2 \sin ^2 \theta _W} \mathopen {}\mathclose {\left(1 + \Delta r \right)},\) 
